As scientists around the world race to develop a cure for coronavirus, there are hopes a century-old vaccine could hold the key.
Analysis has found that countries that use a tuberculosis vaccine called Bacillus Calmette-Guérin (BCG) tend to experience both fewer and less severe cases of Covid-19.
Multiple clinical trials are now examining whether BCG, which was developed in Paris during the 1920s, could protect people from catching coronavirus.
Scientists have known for a long time that the vaccine doesn't just immunise against the bacterial lung infection tuberculosis, but is known to help the body fight off other respiratory illnesses.